Fernando Antonio Souza de Aragão

Muskmelon seed priming in relation to seed vigor

A number of important factors may affect seed priming response, including seed quality. Effects of seed vigor on seed priming response were investigated using seed lots of two muskmelon (Cucumis melo L.) cultivars. Seeds of muskmelon, cvs. Mission and Top Net SR were artificially aged at 43°C for 0, 20 and 40 hours. Seeds were primed for six days in darkness at 25°C in KNO3 (0.35 mol L-1) aerated solution. Aged seeds germinated poorly at 17°C. Priming increased germination rate at 17 and 25°C and germination percentage at 17°C. An interaction effect on germination performance between vigor and priming was observed, especially at low temperature. Priming increased germination performance in seeds of low vigor, and the response was cultivar dependent.

Bioensaio para detecção de sementes de soja transgênicas tolerantes ao glifosato

Abstract – Glyphosate is a systemic, nonselective, postemergence herbicide that inhibits growth ofboth weeds and crop plants. Once inside the plant, glyphosate interferes with biosynthesis of aromaticamino acids phenylalanine, tyrosine, and tryptophan, by inhibiting the activity of5-enolpyruvylshikimate-3-phosphate synthase (EPSPS), a key enzyme of the shikimate pathway.The objective of this work was to develop a simple, effective and inexpensible method for identificationof transgenic soybean tolerant to glyphosate. This technique consisted in germinating soybean seeds infilter paper moistened with 100 to 200 µM of glyphosate. Transgenic soybean seeds tolerant toglyphosate germinated normally in this solution and, between 7 and 10 days, started to develop aprimary root system. However non-transgenic seeds stopped primary root growth and emission ofsecondary roots.Index terms: Glycine max , herbicide resistance, transgenic plants, biosynthesis. Bioensaio para deteccao de sementes de soja transgenicas tolerantes ao glifosato

Caracterização morfológica de germoplasma de alho por análises multivariada componentes principais e variáveis canônicas

The garlic Germplasm Collection maintained by Embrapa Hortalicas comprises 89 accessions, representing the genetic diversity of this crop in the country. Duplicates of the same genotype increase the cost of maintaining the collection, as well as make difficult their agronomic evaluation. The identification of duplicated accessions of the garlic Germoplasm Active Bank was obtained through analysis of 27 variables of morphological characteristics. Genotypic differentiation among thirteen groups was achieved by cluster analysis. The most important features for distinction of these groups through principal components analysis were: plant height with erect leaves at 60 days; plant height with normal leaves at 60 days; leaf insertion angle at 90 days; bulb colour; number of bulblets from sieves one, two, and four; weight of bulblets from sieve two; average weight of bulbs at harvest time; and average bulb weight at threshing time. The most important features for the distinction of group genotype representatives by canonic variables analysis were: plant height with erect leaves at 120 days; plant height with normal leaves at 60 days; leaf insertion angle at 90 days; number of leaves at 60 and 90 days; number of bulbs at harvest time; total number of bulbs; average weight of plants at first day and at 60 days; and average weight of bulbs. Genotype representatives of different groups were distinctly characterised on the basis of 34 parameters, complemented by canonic variables analysis.

Heritability and gain from selection for field resistance against multiple root-knot nematode species (Meloidogyne incognita race 1 and M. javanica) in carrot

AbstractHeritability and gain from selection of traits associated with field resistance to multiple root-knot nematode species were estimated in carrot (Daucus carota L.). Experimental plots were uniformly and simultaneously infested with Meloidogyne incognita race 1 and M. javanica. Forty-seven half-sib families derived from the cv. ‘Brasília’ were evaluated for: (1) percentage of commercial roots with non-galling symptoms (%RNG); (2) percentage of commercial roots with gall symptoms (%RGS) and (3) percentage of non-commercial roots (%NCR). The cultivars ‘Brasília’ (resistant), ‘Carandaí’ (intermediate) and ‘Nova Kuroda’ (susceptible) were employed as standards. Broad-sense heritability estimates were 61.9 % for %RNG; 30.6 % for %RGS and 67.9 % for %NCR. However, the gains from selection were very small for all traits. The genotypic correlation between %RGS and %NCR was –0.38 and the correlation between %RNG and %RGS was 0.13. Selection on increasing %RNG resulted in a negative correlated response on %NCR (genotypic correlation = –0.99) indicating repulsion phase linkage(s) between the genetic factor(s) controlling these traits. The phenotypic correlation of –0.88 between %RNG and %NCR suggested that incomplete penetrance and dosage effects might be involved in the expression of these traits. Selection of superior genotypes (i.e. high %RNG, low %RGS, and low %NCR) can be achieved. ‘Brasília’ was among the genotypes selected for the following cycle of recombination reinforcing the notion that this cultivar is one of the most promising sources of stable, wide-spectrum field resistance to Meloidogyne species in D. carota.

Condicionamento osmótico de sementes de melão: absorção de água e germinação em diferentes temperaturas

Low temperatures (below 17°C) may inhibit muskmelon seed germination. Seed priming may overcome the inhibitory effect of low temperatures and increase germination and seedling establishment in the field. Muskmelon seeds were primed in KNO3 (0.35M) aerated solution for six days at 25°C. Water imbibition during seed priming and germination was determined. Higher germination in both temperatures was observed in primed seeds. Primed seeds absorbed more water and germinated faster than unprimed seeds.

Genetic study with Heliconia psittacorum and interspecific hybrids

Um estudo genetico sobre sete cultivares de H. psittacorum e hibridos interespecificos de Heliconia foi conduzido. O diâmetro da haste (DH) apresentou maior estimativa de herdabilidade (99,32 %), maior coeficiente de variacao genetica (56,90 %) e CVg/CVe (1,85), refletindo uma situacao favoravel para selecao. As correlacoes geneticas de DH com dias para emissao da inflorescencia (DEI) (0,64), periodo desde a emissao do perfilho ate a colheita da inflorescencia (CICLO) (0,63) e massa da haste (MH) (0,96), demonstram que, genotipos com hastes de diâmetro maior, apresentaram maior tempo da emissao a colheita da inflorescencia e maior massa da haste. O comprimento da inflorescencia (CI), DH e DEI foram os caracteres mais importantes, responsaveis por 99,55 % da variacao total. Os valores de repetibilidade foram acima de 0,60 para DH e CI e os coeficientes de determinacao acima de 93 % para DH, MH, DEI e CI.

Cultivo de embriões de tomate in vitro visando a introgressão de genes de Lycopersicon peruvianum em L. esculentum

Three culture media in combination with distinct accessions, crossing generations and periods of time after artificial pollination were evaluated in order to identify more efficient protocols to recover interspecific hybrids between Lycopersicon esculentum and L. peruvianum. Both type of media for seed plating and the interval time for fruit harvest after artificial pollination had significant influence on the recovery of interspecific hybrids. The HLH medium gave the best results. The interval between 25 and 35 days after the artificial pollination was found to be the ideal for recovering interspecific hybrids. For acclimation, the L. esculentum and L. peruvianum plants were evaluated as well as plants of the interspecific hybrids (F1) and those from the RC1 and RC2 generations. This process was affected by the size of the buds used in the seedling transfer before acclimation as well as by the accesses and the time period over which the plantlet was in the test tube. The hybrids presented a better acclimation ability. The ideal period ranged between 26 and 35 days after transferring the seedling to the test tube. The acclimation accomplished under mild environmental conditions improved the plantlet survival.

Screening of melon genotypes for resistance to vegetable leafminer and your phenotypic correlations with colorimetry

Melon is one of the most important vegetable crops in the world. With short cycle in a system of phased planting, phytosanitary control is compromised, and a great volume of agricultural chemicals is used to control vegetable leafminer. Genetic control is an ideal alternative to avoid the damage caused by this insect. Thus, the aim of this study was to evaluate Cucumis accessions in regard to resistance to leafminer and correlate the variables analyzed. Fifty-four accessions and four commercial hybrids of melon were tested. The study was divided into two experiments: with and with no choice. The following characteristics were evaluated: with choice, in field - subjective score based on the infestation and the number of mines per leaf; and with no choice, in cage - number of mines per leaf, chlorophyll content, and leaf colorimetry. The results showed variability among the accessions and some genotypes showed favorable results for resistance in both experiments. There was correlation between the two variables in the experiment in the field. The accessions CNPH 11-282, CNPH 06-1047, and CNPH 11-1077 are the most recommended for future breeding programs with aim on introgression of resistance to vegetable leafminer in melon.

Pollination requirements of seeded and seedless mini watermelon varieties cultivated under protected environment

The objective of this work was to evaluate the floral biology and pollination requirements of seeded and seedless mini watermelon varieties, and to determine the best varieties to cultivate under protected environment. Three seedless (HA‑5106, HA‑5158, and HA‑5161) and two seeded (Minipol and Polimore) genotypes were tested. Flowers were monitored from the pre‑anthesis stage to senescence, and fruit quality was also evaluated. The evaluated treatments were hand‑geitonogamous pollination (MG), cross‑pollination with pollen from the Polimore variety (MCP), cross‑pollination with pollen from the Minipol variety (MCM), and restricted pollination. All varieties had monoecious plants with diclinous flowers, and the stigmas remained receptive throughout anthesis. Fruit set rates of 84.62% (MG), 61.54% (MCP), 48% (MCM), and 0% (restricted) were obtained for seeded varieties, but of 0% (MG), 76.36% (MCP), 82.69% (MCM), and 0% (restricted) for seedless varieties. Fruits did not differ in quality among treatments within each genotype. Therefore, all the studied varieties require a pollination agent and diploid pollen for fruit set to occur, regardless of the donor variety; and Minipol or Polimore with HA‑5106 or HA‑5158 are the varieties recommended for cultivation in protected environment.

Caracterização de frutos de genótipos de muricizeiros cultivados no litoral cearense

Of the species of fruits native to the northeast of Brazil, the nance tree (Byrsonima dealbata Griseb) stands out for offering the potential for both fresh consumption and industrialization. The local populations live by harvesting fruits, and find a source of income in the nance fruit, selling it in street markets. Despite the social importance of those fruit species which are native to certain regions, there is little information about these species. In view of the above, the objective here was to evaluate the fruits of different nance genotypes, using biometric characterization and the genetic relationships between those genotypes. Eighteen genotypes of the nance were analysed, taken from the municipalities of Pacajus, Fortaleza and Paraipaba in the state of Ceara. Thirty measurements were taken, each corresponding to a single fruit, in which the following were analysed: weight, diameter, length, color (L, a*, b*) firmness and yield, this last being based on 100g of pulp. From the results, oblong fruit were predominant, especially the EM 4 genotype which presented the greatest weight. The residual variance, genetic variance, repeatability and phenotypic correlations between variables were all estimated. The multivariate techniques used (genotype clustering using Tocher optimisation, principal-component analysis, and analysis of the dissimilarity of the genotypes expressed as a dendrogram based on nearest-neighbor methodology) had similar results, showing that the three genotypes EM 3, EM 4 and PAC 6 presented different results from each other and the rest of the group, having a genetic variability which would potentially allow for usage in breeding programs.